View source for Biology:Fish migration

{{short description|Movement of fishes from one part of a water body to another on a regular basis}}
[[File:Jumping Salmon.jpg|thumb|right|upright 1.3 |Many species of salmon are anadromous and can migrate long distances up rivers to spawn]]
[[File:Fish Migration.webm|thumb|290px|Allowing fish and other migratory animals to travel the rivers can help maintain healthy fish populations]]

'''Fish migration''' is [[Biology:Animal migration|mass relocation]] by [[Biology:Fish|fish]] from one area or [[Earth:Body of water|body of water]] to another. Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres. Such migrations are usually done for better feeding or to reproduce, but in other cases the reasons are unclear.

Fish migrations involve movements of schools of fish on a scale and duration larger than those arising during normal daily activities.<ref>Dingle, Hugh and Drake, V. Alistair (2007)  "What Is Migration?". ''BioScience'', '''57'''(2):113–121. {{doi|10.1641/B570206}}</ref> Some particular types of migration are ''anadromous'', in which adult fish live in the sea and migrate into fresh water to [[Biology:Spawn|spawn]]; and ''catadromous'', in which adult fish live in fresh water and migrate into salt water to spawn.<ref>{{Cite journal|last1=Gross|first1=Mart R.|last2=Coleman|first2=Ronald M.|last3=McDowall|first3=Robert M.|date=1988-03-11|title=Aquatic Productivity and the Evolution of Diadromous Fish Migration|url=https://www.science.org/lookup/doi/10.1126/science.239.4845.1291|journal=Science|volume=239|issue=4845|pages=1291–1293|doi=10.1126/science.239.4845.1291|pmid=17833216 |bibcode=1988Sci...239.1291G |s2cid=241447 }}</ref>

Marine [[Biology:Forage fish|forage fish]] often make large migrations between their spawning, feeding and nursery grounds. Movements are associated with ocean currents and with the availability of food in different areas at different times of year. The migratory movements may partly be linked to the fact that the fish cannot identify their own offspring and moving in this way prevents [[Biology:Cannibalism|cannibalism]]. Some species have been described by the United Nations Convention on the Law of the Sea as highly migratory species. These are large [[Biology:Pelagic fish|pelagic fish]] that move in and out of the exclusive economic zones of different nations, and these are covered differently in the treaty from other fish.

Salmon and [[Biology:Striped bass|striped bass]] are well-known anadromous fish, and freshwater [[Biology:Eel|eel]]s are catadromous fish that make large migrations. The [[Biology:Bull shark|bull shark]] is a [[Biology:Euryhaline|euryhaline]] species that moves at will from fresh to salt water, and many marine fish make a [[Biology:Diel vertical migration|diel vertical migration]], rising to the surface to feed at night and sinking to lower layers of the ocean by day. Some fish such as [[Biology:Tuna|tuna]] move to the north and south at different times of year following temperature gradients. The patterns of migration are of great interest to the fishing industry. Movements of fish in fresh water also occur; often the fish swim upriver to spawn, and these traditional movements are increasingly being disrupted by the building of dams.<ref name=Woo2019 />

==Classification==
[[File:Ocean migration of Altantic salmon.gif|thumb|right|Ocean migration of Atlantic salmon from Connecticut River<ref>[http://www.fws.gov/r5crc/Stuff/appc.html Atlantic Salmon Life Cycle] {{webarchive |url=https://web.archive.org/web/20140115064920/http://www.fws.gov/r5crc/Stuff/appc.html |date=January 15, 2014}} Connecticut River Coordinator's Office, U.S. Fish and Wildlife Service.</ref>]]

As with various other aspects of fish life, zoologists have developed empirical classifications for fish migrations.<ref name="Secor 2009">{{cite journal|last=Secor |first=David H|author2=Kerr L A|title=Lexicon of life cycle diversity in diadromous and other fishes.|journal=Am. Fish. Soc. Symp.|year=2009|issue=69|pages=537–556}}</ref> The first two following terms have been in long-standing wide usage while others are of more recent coinage.

* '''''Anadromous''''' – fish that migrate from the sea up (Greek: ἀνά ''aná'', "up" and δρόμος ''drómos'', "course") into fresh water to spawn, such as salmon, [[Biology:Striped bass|striped bass]],<ref name="Moyle, P.B 2004">{{cite book | last1=Moyle | first1=Peter B. | last2=Cech | first2=Joseph J. | title=Fishes : an introduction to ichthyology | publisher=Pearson Prentice Hall | publication-place=Upper Saddle River, NJ | date=2004 | isbn=0-13-100847-1 | oclc=52386194}}</ref> and the [[Biology:Sea lamprey|sea lamprey]]<ref name="Silva, S. 2014">Silva, S., Araújo, M. J., Bao, M., Mucientes, G., & Cobo, F. (2014). "The haematophagous feeding stage of anadromous populations of sea lamprey Petromyzon marinus: low host selectivity and wide range of habitats". ''Hydrobiologia'', 734(1), 187–199.</ref>
* '''''Catadromous''''' – fish that migrate from fresh water down (Greek: κατά ''kata'', "down" and δρόμος ''dromos'', "course") into the sea to spawn, such as [[Biology:Eel|eel]]s<ref name="Moyle, P.B 2004" /><ref name=Tyus2012>{{cite book | last=Tyus | first=Harold M. | title=Ecology and conservation of fishes | publisher=CRC Press | publication-place=Boca Raton, FL | date=2012 | isbn=978-1-4398-9759-1 | oclc=1032266421}}</ref>

George S. Myers coined the following terms in a 1949 journal article.
* '''''Diadromous''''' – ''all'' fish that migrate between the sea and fresh water. Like the two aforementioned, well-known terms, ''diadromous'' was formed from Classical Greek ([''dia''], "through"; and [''dromous''], "running").
* '''''Amphidromous''''' – fish that migrate from fresh water to the sea, or vice versa, but not for the purpose of breeding. Instead they enter saltwater or freshwater as larvae, where they will grow into juveniles before returning to the habitat they originally came from and stay there for the rest of their life, growing into sexually mature adults.<ref name="Diadromous fish">[https://www.sciencedirect.com/science/article/pii/S2589004220310348 Investigating Diadromy in Fishes and Its Loss in an -Omics Era]</ref>
* '''''Potamodromous''''' – fish whose migrations occur wholly within fresh water
* '''''Oceanodromous''''' – fish that live and migrate wholly in the sea<ref name="Secor 2009" /><ref name="Myers 1949">{{cite journal|last=Myers| first=George S.| title=Usage of Anadromous, Catadromous and allied terms for migratory fishes| journal =Copeia|year =1949| volume=1949| issue=2| pages=89–97|doi=10.2307/1438482|jstor=1438482}}</ref>

Although these classifications were originated for fish, they are, in principle, applicable to any aquatic organism.

List of diadromous orders and families, and the number of known species:<ref name="Diadromous fish"/><ref>[https://ars.els-cdn.com/content/image/1-s2.0-S2589004220310348-mmc1.pdf Supplemental Information]</ref>

{|class="wikitable"
!Clade
!Order
!Family
!Diadromous
!Anadromous
!Catadromous
!Amphidromous
|-
|rowspan="3"|[[Biology:Cyclostomi|Cyclostomi]]
|rowspan="3"|[[Biology:Lamprey|Lamprey]]s
|[[Biology:Geotriidae|Geotriidae]]
|1
|1
|
|
|-
|[[Biology:Mordaciidae|Mordaciidae]]
|2
|2
|
|
|-
|[[Biology:Petromyzontidae|Petromyzontidae]]
|8
|8
|
|
|-
|[[Biology:Chondrostei|Chondrostei]]
|[[Biology:Acipenseriformes|Acipenseriformes]]
|[[Biology:Sturgeon|Sturgeon]]s
|18
|18
|
|
|-
|rowspan="5"|[[Biology:Elopomorpha|Elopomorpha]]
|rowspan="2"|[[Biology:Elopiformes|Elopiformes]]
|[[Biology:Elopidae|Elopidae]]
|1
|1
|
|
|-
|[[Biology:Tarpon|Tarpon]]s
|1
|
|1
|
|-
|rowspan="3"|[[Biology:Eel|Eel]]s
|[[Biology:Anguillidae|Anguillidae]]
|16
|
|16
|
|-
|[[Biology:Moray eel|Moray eel]]s
|1
|
|1
|
|-
|[[Biology:Ophichthidae|Ophichthidae]]
|1
|1
|
|
|-
|rowspan="11"|[[Biology:Otocephala|Otocephala]]
|rowspan="3"|[[Biology:Clupeiformes|Clupeiformes]]
|[[Biology:Clupeidae|Clupeidae]]
|31
|26
|2
|3
|-
|[[Biology:Anchovy|Anchovies]]
|11
|5
|1
|5
|-
|[[Biology:Pristigasteridae|Pristigasteridae]]
|7
|4
|
|3
|-
|[[Biology:Cypriniformes|Cypriniformes]]
|[[Biology:Cyprinidae|Cyprinidae]]
|6
|6
|
|
|-
|[[Biology:Characiformes|Characiformes]]
|[[Biology:Citharinidae|Citharinidae]]
|2
|2
|
|
|-
|rowspan="6"|[[Biology:Catfish|Catfish]]
|[[Biology:Ariidae|Ariidae]]
|13
|3
|
|10
|-
|[[Biology:Bagridae|Bagridae]]
|1
|1
|
|
|-
|[[Biology:Claroteidae|Claroteidae]]
|1
|1
|
|
|-
|[[Biology:Shark catfish|Shark catfish]]
|1
|1
|
|
|-
|[[Biology:Eeltail catfish|Eeltail catfish]]
|1
|
|
|1
|-
|[[Biology:Schilbeidae|Schilbeidae]]
|1
|
|
|1
|-
|rowspan="2"|[[Biology:Protacanthopterygii|Protacanthopterygii]]
|Galaxiiformes
|[[Biology:Galaxiidae|Galaxiidae]]
|11
|1
|
|10
|-
|Salmoniformes
|[[Biology:Salmonidae|Salmonidae]]
|35
|35
|
|
|-
|rowspan="4"|[[Biology:Stomiati|Stomiati]]
|rowspan="4"|[[Biology:Osmeriformes|Osmeriformes]]
|[[Biology:Smelt (fish)|Smelts]]
|10
|10
|
|
|-
|[[Biology:Ayu sweetfish|Plecoglossidae]]
|1
|
|
|1
|-
|[[Biology:Retropinnidae|Retropinnidae]]
|5
|1
|
|4
|-
|[[Biology:Salangidae|Salangidae]]
|6
|6
|
|
|-
|rowspan="2"|[[Biology:Paracanthopterygii|Paracanthopterygii]]
|rowspan="2"|[[Biology:Gadiformes|Gadiformes]]
|[[Biology:Gadidae|Gadidae]]
|1
|1
|
|
|-
|[[Biology:Lotidae|Lotidae]]
|1
|1
|
|
|-
|rowspan="30"|[[Biology:Percomorpha|Percomorpha]]
|[[Biology:Ovalentaria|Ovalentaria]]
|[[Biology:Ambassidae|Ambassidae]]
|4
|
|1
|3
|-
|rowspan="2"|[[Biology:Atheriniformes|Atheriniformes]]
|[[Biology:Old World silverside|Old World silverside]]s
|1
|
|
|1
|-
|[[Biology:Neotropical silverside|Neotropical silverside]]s
|2
|2
|
|
|-
|Gobiesociformes
|[[Biology:Gobiesocidae|Gobiesocidae]]
|1
|
|
|1
|-
|rowspan="3"|[[Biology:Gobiiformes|Gobiiformes]]
|[[Biology:Eleotridae|Eleotridae]]
|37
|
|5
|32
|-
|[[Biology:Gobiidae|Gobiidae]]
|103
|2
|
|101
|-
|[[Biology:Rhyacichthyidae|Rhyacichthyidae]]
|2
|
|
|2
|-
|Mugiliformes
|[[Biology:Mullet (fish)|Mugilidae]]
|34
|1
|27
|6
|-
|[[Physics:Flatfish|Flatfish]]
|[[Biology:Pleuronectidae|Pleuronectidae]]
|2
|
|2
|
|-
|[[Biology:Syngnathiformes|Syngnathiformes]]
|[[Biology:Syngnathidae|Syngnathidae]]
|5
|
|
|5
|-
|[[Biology:Tetraodontiformes|Tetraodontiformes]]
|[[Biology:Tetraodontidae|Tetraodontidae]]
|2
|2
|
|
|-
|[[Biology:Carangiformes|Carangiformes]]
|[[Biology:Carangidae|Carangidae]]
|2
|
|
|2
|-
|[[Biology:Moroniformes|Moroniformes]]
|[[Biology:Moronidae|Moronidae]]
|2
|2
|
|
|-
|[[Biology:Acanthuriformes|Acanthuriformes]]
|[[Biology:Sciaenidae|Sciaenidae]]
|3
|
|
|3
|-
|rowspan="3"|[[Biology:Scorpaeniformes|Scorpaeniformes]]
|[[Biology:Cottidae|Cottidae]]
|8
|
|2
|6
|-
|[[Biology:Stickleback|Stickleback]]s
|2
|2
|
|
|-
|[[Biology:Scorpaenidae|Scorpaenidae]]<br/>(subfamily [[Biology:Tetraroginae|Tetraroginae]])
|1
|
|1
|
|-
|[[Biology:Trachiniformes|Trachiniformes]]
|[[Biology:Torrentfish|Cheimarrichthyidae]]
|1
|
|
|1
|-
|rowspan="12"|[[Biology:Perciformes|Perciformes]]
|[[Biology:Lutjanidae|Lutjanidae]]
|2
|
|2
|
|-
|[[Biology:Centropomus|Centropomidae]]
|9
|
|2
|7
|-
|[[Biology:Mojarra|Mojarra]]s
|7
|
|
|7
|-
|[[Biology:Haemulidae|Haemulidae]]
|1
|
|
|1
|-
|[[Biology:Flagtail|Flagtail]]s
|10
|
|5
|5
|-
|[[Biology:Lateolabrax|Lateolabracidae]]
|1
|
|1
|
|-
|[[Biology:Latidae|Latidae]]
|1
|
|1
|
|-
|[[Biology:Temperate perch|Temperate perch]]s
|1
|
|1
|
|-
|[[Biology:Percidae|Percidae]]
|1
|1
|
|
|-
|[[Biology:Congoli|Pseudaphritidae]]
|1
|
|1
|
|-
|[[Biology:Terapontidae|Terapontidae]]
|1
|
|1
|
|-
|[[Biology:Archerfish|Archerfish]]
|3
|
|
|3
|-
|Total||||||444||147||73||224
|}

==Forage fish==
[[Image:Capelin-iceland.svg|thumb|right|Migration of Icelandic [[Biology:Capelin|capelin]]]]

[[Biology:Forage fish|Forage fish]] often make great migrations between their spawning, feeding and nursery grounds. Schools of a particular stock usually travel in a triangle between these grounds. For example, one stock of herrings have their spawning ground in southern {{wipe|Norway}},  their feeding ground in Iceland and their nursery ground in northern Norway. Wide triangular journeys such as these may be important because forage fish, when feeding, cannot distinguish their own offspring.<ref name=Woo2019>{{Cite book|last1=Woo|first1=Patrick T. K.|url=https://books.google.com/books?id=4yLKDwAAQBAJ&q=fish+migration&pg=PA125|title=Climate Change and Non-infectious Fish Disorders|last2=Iwama|first2=George K.|date=2019-12-21|publisher=CABI|isbn=978-1-78639-398-2|language=en}}</ref>

[[Biology:Capelin|Capelin]] are a forage fish of the [[Biology:Smelt (fish)|smelt]] family found in the [[Earth:Atlantic Ocean|Atlantic]] and [[Earth:Arctic Ocean|Arctic]] oceans. In summer, they graze on dense swarms of [[Earth:Plankton|plankton]] at the edge of the ice shelf. Larger capelin also eat [[Biology:Krill|krill]] and other [[Biology:Crustacean|crustacean]]s. The capelin move inshore in large schools to spawn and migrate in spring and summer to feed in plankton rich areas between Iceland, [[Place:Greenland|Greenland]] and Jan Mayen. The migration is affected by [[Earth:Ocean current|ocean current]]s. Around Iceland maturing capelin make large northward feeding migrations in spring and summer. The return migration takes place in September to November. The spawning migration starts north of Iceland in December or January.<ref>{{Cite journal|last=Vilhjálmsson|first=H|date=October 2002|title=Capelin (Mallotus villosus) in the Iceland–East Greenland–Jan Mayen ecosystem|journal=ICES Journal of Marine Science|volume=59|issue=5|pages=870–883|doi=10.1006/jmsc.2002.1233|doi-access=free}}</ref>

The diagram on the right shows the main [[Biology:Spawn|spawning]] grounds and larval drift routes. Capelin on the way to feeding grounds is coloured green, capelin on the way back is blue, and the breeding grounds are red.

In a paper published in 2009, researchers from Iceland recount their application of an interacting particle model to the capelin stock around Iceland, successfully predicting the spawning migration route for 2008.<ref>Barbaro1 A, Einarsson B, Birnir1 B, Sigurðsson S, Valdimarsson S, Pálsson ÓK, Sveinbjörnsson S and Sigurðsson P (2009)  [http://escholarship.ucop.edu/uc/item/1jv6n689.pdf "Modelling and simulations of the migration of pelagic fish"] ''Journal of Marine Science'', '''66'''(5):826-838.</ref>

==Highly migratory species==
[[File:internationalwaters.png|right|thumb|The high seas, highlighted in blue, are the seas which are outside the {{convert|200|nmi|km|abbr=on}} exclusive economic zones]]

The term '''highly migratory species''' (HMS) has its origins in Article 64 of the United Nations Convention on the Law of the Sea (UNCLOS). The Convention does not provide an operational definition of the term, but in an annex (UNCLOS Annex 1) lists the species considered highly migratory by parties to the convention.<ref>{{wipe|United Nations}} Convention on the Law of the Sea:  [https://www.un.org/Depts/los/convention_agreements/texts/unclos/closindx.htm Text]</ref> The list includes: [[Biology:Tuna|tuna]] and tuna-like species (albacore, [[Biology:Bluefin tuna|bluefin]], [[Biology:Bigeye tuna|bigeye tuna]], [[Biology:Skipjack tuna|skipjack]], [[Biology:Yellowfin tuna|yellowfin]], [[Biology:Blackfin tuna|blackfin]], little tunny, [[Biology:Southern bluefin tuna|southern bluefin]] and bullet), [[Biology:Wahoo|wahoo]], pomfret, [[Biology:Marlin|marlin]], [[Biology:Sailfish|sailfish]], [[Biology:Swordfish|swordfish]], [[Biology:Saury|saury]] and  oceangoing [[Biology:Shark|shark]]s, [[Biology:Dolphin|dolphin]]s and other [[Biology:Cetacea|cetaceans]].

These high [[Earth:Trophic level|trophic level]] oceanodromous species undertake migrations of significant but variable distances across oceans for feeding, often on forage fish, or reproduction, and also have wide geographic distributions. Thus, these species are found both inside the {{convert|200|nmi|km|adj=on|abbr=off}} [[Earth:Exclusive economic zone|exclusive economic zone]]s and in the high seas outside these zones. They are [[Biology:Pelagic fish|pelagic]] species, which means they mostly live in the open ocean and do not live near the sea floor, although they may spend part of their life cycle in nearshore waters.<ref>Pacific Fishery Management Council: [http://www.pcouncil.org/highly-migratory-species/background/  Background:  Highly Migratory Species]</ref>

Highly migratory species can be compared with straddling stock and transboundary stock. Straddling stock range both within an EEZ as well as in the high seas. Transboundary stock range in the EEZs of at least two countries. A stock can be both transboundary and straddling.<ref name="FAO 2007">FAO (2007) [https://agris.fao.org/agris-search/search.do?recordID=XF2016072968 Report of the FAO workshop on vulnerable ecosystems and destructive fishing in deep sea fisheries], Rome, Fisheries Report No. 829. [https://books.google.com/books?id=6jL7ZHq9GgsC&pg=PA1 HTML]</ref>

It can be challenging to determine the population structure of highly migratory species using physical tagging. Traditional genetic markers such as short-range PCR products, microsatellites and SNP-arrays have struggled to identify population structure and distinguish fish stocks from separate ocean basins. However, [[Biology:Population genomics|population genomic]] research using [[Biology:Restriction site associated DNA markers|RAD]] sequencing in yellowfin tuna,<ref name="Grewe-2015">{{cite journal |doi=10.1038/srep16916 |title=Evidence of discrete yellowfin tuna (''Thunnus albacares'') populations demands rethink of management for this globally important resource |journal=Scientific Reports |volume=5 |pages=16916 |year=2015 |last1=Grewe |first1=P.M. |last2=Feutry |first2=P. |last3=Hill |first3=P.L. |last4=Gunasekera |first4=R.M. |last5=Schaefer |first5=K.M. |last6=Itano |first6=D.G. |last7=Fuller |first7=D.W.  |last8=Foster |first8=S.D.  |last9=Davies |first9=C.R. |pmid=26593698 |pmc=4655351 |bibcode=2015NatSR...516916G |doi-access=free}}</ref><ref name="Pecoraro-2018">{{cite journal |doi=10.1038/s41598-018-32331-3 |title=The population genomics of yellowfin tuna (''Thunnus albacares'') at global geographic scale challenges current stock delineation |journal=Scientific Reports |volume=8 |pages=13890 |year=2018 |last1=Pecoraro|first1=Carlo |last2=Babbucci |first2=Massimiliano |last3=Franch |first3=Rafaella |last4=Rico |first4=Ciro |last5=Papetti |first5=Chiara |last6=Chassot |first6=Emmanuel |last7=Bodin |first7=Nathalie  |last8=Cariani |first8=Alessia  |last9=Bargelloni |first9=Luca |last10=Tinti |first10=Fausto |issue=1 |pmid=30224658 |pmc=6141456 |bibcode=2018NatSR...813890P |doi-access=free}}</ref>  albacore,<ref name="Anderson-2019">{{cite journal |doi=10.1002/ece3.5554 |title=Indications of strong adaptive population genetic structure in albacore tuna (''Thunnus alalunga'') in the southwest and central Pacific Ocean |journal=Ecology and Evolution |volume=9 |issue=18 |pages=10354–10364 |year=2019 |last1=Anderson|first1=Giulia |last2=Hampton |first2=John |last3=Smith |first3=Neville |last4=Rico |first4=Ciro |pmid=31624554 |pmc=6787800 |doi-access=free}}</ref><ref name="Vaux-2021">{{cite journal |doi=10.1111/eva.13202 |title=Adaptive markers distinguish North and South Pacific Albacore amid low population differentiation |journal=Evolutionary Applications |volume=14 |issue=5 |pages=1343–1364 |year=2021 |last1=Vaux|first1=Felix |last2=Bohn|first2=Sandra |last3=Hyde|first3=John R. |last4=O'Malley |first4=Kathleen G. |pmid=34025772 |pmc=8127716 |doi-access=free}}</ref> and wahoo<ref name="Haro-Bilbao-2021">{{cite journal |doi=10.1111/jbi.14135| issn=0305-0270 |title=Global connections with some genomic differentiation occur between Indo-Pacific and Atlantic Ocean wahoo, a large circumtropical pelagic fish |journal=Journal of Biogeography |volume= 48|issue= 8|pages= 2053–2067|year=2021 |last1=Haro-Bilbao|first1=Isabel |last2=Riginos|first2=Cynthia |last3=Baldwin|first3=John D. |last4=Zischke |first4=Mitchell |last5=Tibbetts |first5=Ian R. |last6=Thia |first6=Joshua A.|s2cid=236381627 |hdl=11343/298583 |hdl-access=free }}</ref> has been able to distinguish populations from different ocean basins and reveal fine-scale population structure. Similar population genomics methods have also provided improved insight towards population structure in [[Biology:Striped marlin|striped marlin]].<ref name="Mamoozadeh-2020">{{cite journal |doi=10.1111/eva.12892 |title=Genome‐wide SNPs resolve spatiotemporal patterns of connectivity within striped marlin (''Kajikia audax''), a broadly distributed and highly migratory pelagic species |journal=Evolutionary Applications |volume=13 |issue=4 |pages=677–698 |year=2020 |last1=Mamoozadeh|first1=Nadya R. |last2=Graves |first2=John E. |last3=McDowell |first3=Jan R. |pmid=32211060 |pmc=7086058 |doi-access=free}}</ref>

==Other examples==

Some of the best-known anadromous fishes are the Pacific salmon species, such as [[Biology:Chinook salmon|Chinook]] (king), [[Biology:Coho salmon|coho]] (silver), [[Biology:Chum salmon|chum]] (dog), [[Biology:Pink salmon|pink]] (humpback) and [[Biology:Sockeye salmon|sockeye]] (red) salmon.  These salmon hatch in small freshwater streams. From there they migrate to the sea to mature, living there for two to six years. When mature, the salmon return to the same streams where they were hatched to spawn. Salmon are capable of going hundreds of kilometers upriver, and humans must install [[Biology:Fish ladder|fish ladder]]s in dams to enable the salmon to get past. Other examples of anadromous fishes are [[Biology:Sea trout|sea trout]], [[Biology:Three-spined stickleback|three-spined stickleback]], [[Biology:Sea lamprey|sea lamprey]] and <ref name="Silva, S. 2014"/> shad.

Several Pacific salmon (Chinook, coho and Steelhead) have been introduced into the US Great Lakes, and have become potamodromous, migrating between their natal waters to feeding grounds entirely within fresh water.

[[File:Lake Washington Ship Canal Fish Ladder pamphlet - life cycle chart.jpg|thumb|right|Life cycle of anadromous fish. From a U.S. Government pamphlet. (Click image to enlarge.)]]

[[Biology:Eel life history|Remarkable catadromous migrations]] are made by freshwater eels. Examples are the [[Biology:American eel|American eel]] and the [[Biology:European eel|European eel]] which migrate huge distances from freshwater rivers to spawn in the Sargasso sea, and whose subsequent larvae can drift in currents for months and even years before returning to their natal rivers and streams as glass eels or elvers.

An example of a [[Biology:Euryhaline|euryhaline]] species is the [[Biology:Bull shark|bull shark]], which lives in Lake Nicaragua of Central America and the Zambezi River of Africa. Both these habitats are fresh water, yet bull sharks will also migrate to and from the ocean. Specifically, Lake Nicaragua bull sharks migrate to the Atlantic Ocean and Zambezi bull sharks migrate to the Indian Ocean.

[[Biology:Diel vertical migration|Diel vertical migration]] is a common behavior; many marine species move to the surface at night to feed, then return to the depths during daytime.

A number of large marine fishes, such as the [[Biology:Tuna|tuna]], migrate north and south annually, following temperature variations in the ocean. These are of great importance to fisheries.

Freshwater (potamodromous) fish migrations are usually shorter, typically from lake to stream or vice versa, for spawning purposes. However, potamodromous migrations of the endangered Colorado pikeminnow of the Colorado River system can be extensive. Migrations to natal spawning grounds can easily be 100&nbsp;km, with maximum distances of 300&nbsp;km reported from radiotagging studies.<ref name=Lucas2001>{{cite book | last1=Lucas | first1=Martyn C. | last2=Baras | first2=Etienne | title=Migration of freshwater fishes | publisher=Blackwell Science | publication-place=Oxford | date=2001 | isbn=978-0-470-99965-3 | oclc=212130719}}</ref> Colorado pikeminnow migrations also display a high degree of homing and the fish may make upstream or downstream migrations to reach very specific spawning locations in whitewater canyons.<ref name=Tyus2012 />

Sometimes fish can be dispersed by birds that eat fish eggs. They carry eggs in the digestive tracts and then deposit them in their faeces in a new place. The survival rate for fish eggs that have passed through a bird's digestive tract is low.<ref>{{Cite web|title=Experiment shows it is possible for fish to migrate via ingestion by birds|url=https://phys.org/news/2020-06-fish-migrate-ingestion-birds.html|access-date=2020-06-23|website=phys.org|language=en}}</ref>

==Historic exploitation==
Since prehistoric times humans have exploited certain anadromous fishes during their migrations into freshwater streams, when they are more vulnerable to capture. Societies dating to the Millingstone Horizon are known which exploited the anadromous fishery of Morro Creek<ref>C.M. Hogan, 2008</ref> and other [[Earth:Pacific Ocean|Pacific coast]] [[Earth:Estuary|estuaries]]. In Nevada the Paiute tribe has harvested migrating Lahontan cutthroat trout along the Truckee River since prehistoric times. This fishing practice continues to current times, and the U.S. Environmental Protection Agency has supported research to assure the water quality in the Truckee can support suitable populations of the Lahontan cutthroat trout.

== Myxovirus genes ==
Because [[Biology:Salmonidae|salmonids]] live an anadromous lifestyle, they encounter a larger range of viruses from both freshwater and marine ecosystems. Myxovirus resistance (Mx) proteins are part of a [[Biology:GTPase|GTP-ase]] family that aid in viral immunity, and previously, rainbow trout (''[[Biology:Rainbow trout|Oncorhynchus mykiss]]'') had been shown to possess three different Mx genes to aid in viral defence in both environments. The number of Mx genes can differ among species of fish, with numbers ranging from 1 to 9 and some outliers like [[Biology:Gadiformes|Gadiformes]] that have totally lost their Mx genes. A study was performed by Wang et al. (2019)<ref>{{Cite journal|last=Wang|first=T.|date=2019|title=Lineage/species-specific expansion of the Mx gene family in teleosts: Differential expression and modulation of nine Mx genes in rainbow trout Oncorhynchus mykiss|journal=Fish and Shellfish Immunology|volume=90|pages=413–430|doi=10.1016/j.fsi.2019.04.303|pmid=31063803|hdl=2164/14229|s2cid=147706565 |hdl-access=free}}</ref> to identify more potential Mx genes that resided in rainbow trout. An additional six Mx genes were identified in that study, now named Mx4-9. They also concluded that the trout Mx genes were "differentially expressed constitutively in tissues" and that this expression is increased during development. The Mx gene family is expressed at high levels in the blood and intestine during development, suggesting they are a key to immune defense for the growing fish. The idea that these genes play an important role in development against viruses suggests they are critical in the trout's success in an anadromous lifestyle.

==See also==
* {{annotated link|Earth:Animal navigation}}
* {{annotated link|Earth:Hydrological transport model}}
* {{annotated link|Biology:Semelparity and iteroparity}}
* {{annotated link|Company:Ocean Tracking Network}}
* {{annotated link|Organization:Pacific Ocean Shelf Tracking Project}}
* {{annotated link|Biology:Tagging of Pacific Predators}}

==Notes==
{{reflist|30em}}

==References==
* Blumm, M (2002) [http://www.powells.com/biblio/1-9075228252-0 ''Sacrificing the Salmon: A Legal and Policy History of the Decline of Columbia Basin Salmon''] Bookworld Publications.
* Bond, C E (1996) ''Biology of Fishes'', 2nd ed. Saunders, pp.&nbsp;599–605.
* Hogan, C M (2008) [http://www.megalithic.co.uk/article.php?sid=18502 ''Morro Creek''], The Megalithic Portal, ed. by A. Burnham
* [https://web.archive.org/web/20110218234856/http://www.idrc.ca/en/ev-58888-201-1-DO_TOPIC.html Appendix A: Migratory Fish Species in North America, Europe, Asia and Africa] in Carolsfield J, Harvey B, Ross C and Anton Baer A (2004) ''Migratory Fishes of South America'' World Fisheries Trust/World Bank/IDRC. {{ISBN|1-55250-114-0}}.

==Further reading==
* Ueda H and Tsukamoto K (eds) (2013) [https://books.google.com/books?id=ohwbAAAAQBAJ&dq=%22Physiology+and+Ecology+of+Fish+Migration%22&pg=PP1 ''Physiology and Ecology of Fish Migration''] CRC Press. {{ISBN|9781466595132}}.

==External links==
* {{wipe|United Nations}}: [https://web.archive.org/web/20090201132408/http://www.cms.int/about/intro.htm Introduction to the Convention on Migratory Species]
* [https://web.archive.org/web/20110607043617/http://www.livingnorthsea.eu/ Living North Sea] – International project on tackling fish migration problems in the North Sea Region
* [http://www.linkedin.com/groups?mostPopular=&gid=1215847 Fish Migration Network] – Worldwide network of specialist working on the theme fish migration

{{collective animal behaviour|state=expanded}}
{{diversity of fish}}


{{DEFAULTSORT:Fish Migration}}
[[Category:Ichthyology]]
[[Category:Aquatic ecology]]

{{Sourceattribution|Fish migration}}